The v16 release notes are problematic in a PDF docs build:
[WARN] FOUserAgent - Glyph "?" (0x142, lslash) not available in font "Times-Roman".
This is evidently from
Add functions to add, subtract, and generate timestamptz values in a specified time zone (Przemysław Sztoch, Gurjeet Singh)
Change date_trunc(unit, timestamptz, time_zone) to be an immutable function (Przemysław Sztoch)
since "ł" doesn't exist in ISO8859-1. I'd suggest dumbing these
down to plain "l".
regards, tom lane